Circuit breaker



Dec. 15, 1942. .1.6. JACKSON 2,305,347

v clRcUlT BREAKER original Filed July 25, 19:56

E. 1 A E.

VE N T OR BY 755,7 4 gfzjm A TTORNE Y Patented Dec. 15, 1942 CIRCUIT BREAKER John G. Jackson, Detroit, Mich., assignor to Square D Company, Detroit, Mich., a corporation of Michigan riginal application July 25, 1936, Serial No.

1939, serial No. 264,798

` (ci. 20o-106) 7 Claims.

This invention relates to devices for making and breaking electric circuits and more particularly to electric circuit breakers automatically operable in response to current overload.

An object of the invention is the provision in an electric circuit breaker of a simple and economical current responsive magnetic tripping means together with simple and effective calibrating means for adjusting the value of current to which the circuit breaker is responsive.

Other objects and features of the invention will be readily apparent to those skilled in the art from the following specification and appended drawing illustrating certain preferred embodiments of the invention in which:

Figure l is a front elevational view of the circuit breaker according to the present invention with the front cover and the circuit breaker handle removed to more clearlyfshow the internal parts.

Figure 2 is a vertical sectional view on the line 2-2 of Figure l.

Figure 3 is a partial sectional view of a modified form of trip unit for the circuit breaker mechanism.

This application is a division of application Serial No. 92,644, filed July 25, 1936, for Circuit Breakers, which application became Patent No. 2,177,774 on October 31, 1939.

The circuit breaker according to the present invention comprises an insulating base I of generally cup shape. Within the chamber formed by side walls 2 and 3 of the base, is mounted the stationary contact plate 4 by means of a stud 5.

In order that the circuit breaker here illustrated by the drawing may be placed in conducting relation with other circuit breakers as disclosed in the above noted parent application, or to provide for connection to circuit wirings, there is provided a conducting connector 6 extending through an opening in the wall 2. The contact plate 4 carries a contact surface 'l and has cooperating therewith a contact surface at one end of an elongated floating contact member 8. The arc chamber surrounding these cooperating contact surfaces may be provided with a fiber liner 9 and a fiber barrier II, having a slot I2 closely receiving the contact member 8. The contact member 8 has a double notch engagement with one leg of a rectilinearly movable U-shaped element I3 suitably guided for movement at right angles to the back of the base by guiding projections therein. The compression spring I4 biases the contact member 8 against the stationary ccn- Divided and this application March 29,

after described. An operating handle I8 is pivotally mounted on a shaft I5 mounted within suitable notches I6 in the side walls 2 and 3 of the base. This handle is provided with an interior cam surface cooperating with the front face of the element I3 to move it rectilinearly and including a flat portion II, forming a stable manual off support for the element. The position of the various parts when in the off position is shown in dotted representation in Figure 2.

A light spring I8 biases the handle for rotation in a counter-clockwise direction as shown.

A metallic cover I9, having an opening therein through which the handle I0 is received, is sealably secured to the base by means of spun over rivets or in any other desired manner. Beneath the metallic cover plate I9 is provided a ber sheet 2l] having an end portion 2| serving to seal off the end of the circuit breaker enclosure.

At the end of the enclosure opposite the stationary contact plate 4 is mounted a conducting support 22 as by means of a spun over portion of a metallic insert 23. To the interior end of the support 22 is welded or otherwise secured an L shaped magnetic bracket 24 to the end of which is pivotally mounted a magnetic armature latch member 25 adapted to be engaged with the end of the contact member 8 to latch it in its operating position. The armature 25 is biased away from the bracket 24 by means of a compression spring 26 and its movement therefrom is limited by stud 21 threaded into armature 25 and having its body portion slidable within an opening in the bracket 24. Through the attached portion of the bracket 24 is threaded a magnetic screw 28 having its upper end headed about a generally U shaped member 29 which has its legs suitably guided in notches in the support 22. A flexible lead 3l interconnects the conducting support 22 and the contact member 8. This lead is wound about the magnetic screw 28 and the windings are retained in place by the U-shaped member 29.

The interior end of the magnetic screw 28 forms a pole face adapted to attract the armature 25 upon the occurrence of a predetermined overload current about the magnetic path formed by the bracket 24, the armature 25 and the screw 28. The adjustment of the stud 21 will vary the overlap of the armature latch 25 with the end of the contact member 8 and will have some effect upon the air gap in the magnetic circuit. Adjustment of the screw 28 will directly vary the air gap and these two adjustments together with the lnumber of turns of flexible lead 3| about tact surface 'and a latching surface to be herein- 55 the magnetic screw will determine the value of the current which will trip the breaker mechanlsm.

The operation of the circuit breaker mechanism vwill now be described.

Rotation of the handle I0 about its pivoted l5 will eiiect reciprocation of the element When the fiat portion I'I of the cam surface engages the front surface on the element I3 the stable ofi position will be produced with the contact member 8 rotated about its latchirig engagement with armature 25 to disengage its contact carrying end from the stationary contact surface 'I as is shown in dotted representation in Figure 2.

The circuit breaker is adapted to open the circuit upon the occurrence of a predetermined overload without delay. Upon the occurrence of this predetermined value, the armature 25 will be pulled into engagement with the pole face formed by the end of the magnetic screw 28.

This releases the latching end of the contact members 8 and permits it to rotate about its engagement with element I3 in a counter-clockwise direction under the bias of the spring I4, thus interrupting the current. This release will permit the spring I4 to overcome the spring I8 and will rotate the operating handle to indicating positions. To reset breaker mechanism after an automatic trip, the handle is rotated beyond the manual off position until the tip beyond the fiat I'I moves the element I3 far enough toward the base so that the latching end of the contact member 8 will be re-rotated into position beyond the armature latch 25. Release of the handle will place the parts in the manual off position with the fiat I1 engaging the element I3 whereupon rotation of the handle beyond the fiat will again permit the parts to assume the normal closed circuit position.

A slightly modified form of' trip unit for the circuit breaker mechanism has been illustrated in Figure 3. Here the conducting support 22 has been extended to receive the adjusting stud 32, bearing against a magnetic portion 33 which is Welded or otherwise secured to the support 22 and to the free end of which is secured a magnetic spring latching member 34. The other parts remain the same as in the preferred form of tripping unit. Here the overlap of the spring latch 34 is determined by the adjustment of the stud 32. This latch 34 must be sufliciently rigid to withstand the thrust of the contact member 8 but must have sufficient resilience so as to permit bending under the attraction of the magnetic field so as to permit the latch 34 to move as an armature into engagement with the pole face formed by the magnetic screw 28.

While certain preferred embodiments of the invention have been specifically disclosed, it is understood that the invention is not limited thereto as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretation within the terms of the following claims.

What is claimed is:

1. In an automatic electric circuit breaker, relatively movable contacts, means for moving said contacts to separated position, current responsive means for restraining such movements of said contacts and member forming a part of a magnetic circuit, a conducting connector leading to the exterior of the circuit breaker, a flexible lead interconnecting the movable contact to said conducting connector and having at least a portion thereof including an armature Iii) freely movable with the movable contact wltholz; substantial resistance to thc movement thereof, said flexible lead being wound around a part of said magnetic circuit to render its magnetic field responsive to the current flowing through the circuit breaker.

2. An automatic electric circuit breaker, a stationary contact, a movable contact, means for moving said movable contact to separated position, a latch restraining such movement of the movable contact, said latch constituting an armature arm of a magnetic circuit, a terminal for said circuit breaker, and a flexible lead connecting said movable contact to said terminal and having at least a portion thereof freely movable with the movable contact without substantial resistance to the movement thereof, said lead being wound around a portion of said magnetic circuit to render the magnetic flux therein responsive to the current through the circuit breaker.

3. In an automatic electric circuit breaker, a stationary contact, a movable contact, means for automatically moving said movable contact to separated position, means restraining said. movable contact from such movement, said last mentioned means being movable upon current overload to release the movable contact for automatic movement, and means for effecting the releasing movement of the restraining means including a stationary field magnet, a circuit terminal for the circuit breaker, means connecting the movable contact to the circuit terminal, said connecting means including a flexible lead having at least a portion thereof freely movable with the movable contact without substantial resistance to the movement thereof, said flexible lead v being Wound around a part of said magnet to render its magnetic field responsive to the current flowing through the circuit breaker.

4. In an automatic electric circuit breaker, stationary and movable contacts, means for moving the movable Contact to separated position, current responsive means for initiating action of said first mentioned means for moving the movable contact and including an armature member forming a part of a magnetic circuit, terminal means for the circuit breaker, means interconnecting the movable contact and the terminal means and including a flexible lead having at least a portion thereof freely movable with the movable contact wit-hout substantial resistance to the movement thereof, said flexible lead being wound around a parl of said magnetic circuit to render its magnetic field responsive to the current owing through the circuit breaker.

5. In an automatic electric circuit breaker, stationary and movable contacts, means for moving the movable contact to separated position. current responsive means for initiating action of said first mentioned means for moving the movable contact and including an armature member forming a part of a magnetic circuit, terminal means for the circuit breaker, means interconnecting the movable contact and the terminal means and including a flexible lead having at least a portion thereof freely movable with the movable contact without substantial resistance to the movement thereof, said flexible lead being wound around a part of said magnetic circuit to render its magnetic field responsive to the current flowing through the circuit breaker, and means for adjusting the spacing between the armature member and the portion of the magnetic circuit with which it cooperates in attracted position,

whereby the calibration of the magnetic circuit may be varied.

6. In an automatic electric circuit breaker, stationary and movable contacts, means for moving the movable contact to separated position, current responsive means for initiating action of said first mentioned means for moving the movable contact and including an armature member forming a part of a magnetic circuit, terminal means for the circuit breaker, means interconnecting the movable contact and the terminal means and including a ilexible lead having at least a portion thereof freely movable with the movable contact without substantial resistance to the movement thereof, said flexible lead being wound around a part of said magnetic circuit to render its magnetic eld responsive to the current flowing through the circuit breaker, said magnetic circuit including a sheet metal element of magnetic material having a magnetic pole face mounted there-y on and with the armature pivoted adjacent one end thereof, the flexible lead being wound around the pole piece to effect energization of the magnetic circuit.

7. In an automatic electric circuit breaker, stationary and movable contacts, means for moving the movable contact to separated position, current responsive means for initiating action of said viirst mentioned means for moving the movable contact and including an armature member forming a. part of a magnetic circuit, terminal means for the circuit breaker, means interconnecting the movable contact and the terminal means and including a iiexible lead having at 

